US3260120A - Sampling device - Google Patents

Description

July 12, 1966 D. w. STILWELL 3,260,120

SAMPLING DEVICE Filed Feb. 17, 1964 INVENTOR. DAZ/V 14 57% W5 am PM United States Patent tion of Delaware Filed Feb. 17, 1964, Ser. No. 345,231

1 Claim. (Cl. 73422) This invention relates to a device for sampling fluids and particularly to a device for removing small quantrt es of fluids conveyed through pneumatic condults or pipe lines.

In various manufacturing processes it is necessary to intermittently withdraw samples of material from a flowing stream of a fluid product passing through a conduit which will be representative of the product. A spec fic application is that of sampling a fluid stream contalnlng fines or pellets of industrial chemical products such as polyethylene or other polyolefin compositions. Generally, in such installations it is usual to provide a fluld sampling device having a sampling tube pOSlilOIlCd so as to permanently protrude into the stream of fluid.

A number of problems are frequently encountered in sampling devices of this nature. For example, prior art sampling devices having tubes constantly present in the main fluid stream may cause the entrapment of fines or pellets of polyethylene or other polyolefins thereby creating an aggregation of these materials about the sampling tube. Upon a sufliciently large aggregation of these materials, a flaking-off of lumps or large particles thereof will occur, and the flaked-off materials will consequently be carried into the main product fluid stream thereby contaminating the product. Thus, in polyethylene (or other polyolefins) manufacture, various products of different melt indices, densities and/or molecular weights are usually conveyed through the same pneumatic conduits and pellets or powders of one type entrapped or held on permanent sampling devices can readily contaminate another type of product conveyed subsequently through the same conduit. This cross-contamination is often serious enough to cause thedowngrading of an otherwise prime lot of product due to tight product specifications, thereby entailing an economic loss. Further, the permanent presence of the protruding sampling tube in the fluid stream is an obstruction to the smooth flow of product and may cause turbulence in the fluid stream resulting in an uneven distribution of material and consequent undesirable eflects on the quality and nature of the product.

One object of the present invention is to provide an improved sampling device for fluids which avoids the problems encountered with the use of prior art sampling devices, as set forth hereinabove.

Another object of the present invention is to provide a sampling device which may be removed from the conduit and fluid stream when not engaged in a sampling operation.

Still another object of the present invention is to pro vide a sampling device in which the sampling tube when not engaged in a sampling operation may be retracted to form a continuous surface with the inner wall of the conduit, thereb preventing the aggregation of fines or pellets of polyethylene or other polyolefin materials.

In its broad aspects, the present invention contemplates a sampling device for fluids which comprises a conduit for carrying the fluid to be sampled, a tubular member attached to and projecting from the conduit and adapted to mate with an opening in the latter; a piston slidingly positioned within the tubular member and adapted to be advanced into said conduit at predetermined intervals; the piston having a passageway extending therethrough and permitting flow of fluid from the conduit when the piston is in its advanced position and preventing flow of fluid therethrough when the piston is in a retracted position. As used herein, the term fluid or fluids indicates solids such as powders, pellets and the like which are conveyed or flowed by gravity or pneumatic means through conduits such as pipes, etc. from one area to another.

Other objects and advantages of the present invention will become apparent by referring to the detailed description in the specification and preferred embodiment in the accompanying drawings which form a part of this invention, wherein:

FIGURE 1 is a front elevational view partially in section showing the sampling device of the invention in retracted non-operative position; and

FIGURE 2 is a side elevational view of the sampling device with portions broken away to provide a partial sectional view and with the device shown in extended operative position.

As shown in FIGURE 1, sampling device 10 is attached to a conduit 12 which can be a portion of a pipe line system. The sampling device 10 includes a tubular portion or member 14 attached to the conduit 12 in alignment with an opening 12a in the conduit wall. A piston 16 having a portion of enlarged diameter 16a is reciprocally supported within said tubular member 14 and is adapted to slidingly move in close contact with the inner wall of tubular member 14. The end of the piston 16 protruding into the conduit 12 through opening 12a is preferably shaped to provide a surface 16b conforming substantially to the inner wall contour of the conduit 12. A passageway 18 is provided in piston 16, generally coaxial with the longitudinal centerline of the piston and preferably has a port 18a extending substantially perpendicular to the passageway 18 through surface 16a of the piston near the end of the piston adjacent the conduit 12. The passageway 18 then leads to a second opening or port 18b at the distal end of the piston 16, the latter of which is adapted to engage an attachment 20 for a sampling bag (not shown).

The sampling bag attachment 20 may be provided with an annular recess portion 22 adapted to provide an attaching surface for the sampling bag, and with an annular flange portion 24 which is designed to contact a bushing or closure member 26 threadingly attached to the tubular portion 14. The closure member 26 provides for the retention of the piston within the tubular portion 14 and prevents the piston 16 from overtraveling during retraction.

The closure member 26 can also be provided with one or more resilient spring clips 28 which are adapted to engage flange portion 24 on the sample bag attachment 20 and retain the latter in the fully advanced position of piston 16 during a sampling operation (FIGURE 2). The closure member 26 may also be provided with a set screw 32 adapted to engage a slot 30 provided in the outer wall of the piston 16 in order to prevent rotation of the latter and thus assure positioning of port 18a in the direction of the flow of the fluid stream within conduit 12. In order to indicate to a viewer that port 18a is positioned correctly with respect to the direction of flow of the fluid stream, a scribe line 34 may be provided on the outer surface of the piston 16.

FIGURE 2 depicts the sampling device 10 in its operative sampling position with the piston 16 being fully ad vanced into the conduit 12. At this point, flange portion 24 of attachment 20 abuts against closure member 26 and is firmly held in this position under the urging of spring clips 28 which are now located below the flange portion 24. Port 18a in the piston 16 preferably faces in the direction of the fluid stream (shown through arrows) and samples of the fluid are thus permitted to flow through port 18a and passage 18 into a sampling bag fastened to attachment 20. When the desired quantity of sample material has been collected, the spring clips 28 may be manually deflected radially outwardly thereby disengaging flange portion 24 and permitting the manual movement of the piston 16 to the retracted position shown in FIGURE 1. When piston 16 reaches its retracted position upon the portion 16a of piston 16 abutting against closure member 26, port 18a will be sealed off from the conduit 12, thereby preventing flow of fluid through passage 18 and placing the sampling device 10 into its inoperative position. At that time the surface 16a of piston 16 will substantially blend with the inner wall contour of the conduit 12, thus providing an unrestricted, substantially smooth fiow passage for the fluid stream passing through the conduit.

While particular embodiments of this invention are shown above, it will be understood that the apparatus of this invention is obviously subject to variations and modifications without departure from its broader aspects.

What is claimed is:

A polyolefin pellet sampling device which comprises:

(a) a conduit for carrying pellets to be sampled,

(b) an open-ended tubular member attached at one end to the wall of said conduit and projecting outwardly from said conduit, said tubular member being in alignment with an opening in said conduit,

(c) a piston reciprocally supported within said tubular member whereby one end thereof can be alternately advanced into said conduit and retracted therefrom, said piston including a passageway adapted to convey pellets from said conduit through the entire length of said piston when said piston is in an advanced position, the end portion of said piston adjacent to said conduit containing a port in fluid communication With said passageway and extending substantially perpendicular thereto, the portion of said piston which forms said port forming a substantially continuous surface with the inner Wall of said conduit when said piston is in a retracted position to prevent fiow of pellets andtthe distal end of said piston containing an opening in coaxial alignment with said passageway,

(d) means connected to said distal end of said piston for attaching a receptacle adapted to collect pellets passing through said port, pasageway and opening,

(e) a closure member attached to the end of said tubular member opposite said conduit for retaining said piston within said tubular member and for preventing said piston from overtraveling during retraction and (f) at least one manually operable spring clip member attached to said closure member for retaining said piston in an advanced position within said conduit.

References Cited by the Examiner UNITED STATES PATENTS 1,649,241 11/1927 Lewis 73422 2,370,260 2/1945 Robinson 73-422 2,475,857 7/1949 Reinert 73422 3,066,539 12/1962 Coker et al 73422 X LOUIS R. PRINCE, Primary Examiner.

S. C. SWISHER, Assistant Examiner.

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